The present invention relates to retroreflective sheeting employing microprism formations to retroreflect the light rays impinging thereon, and, more particularly, to a method for producing flexible retroreflective sheet material which may be readily attached to support structures.
Retroreflective sheet material is widely employed for a variety of safety and decorative purposes, and is particularly useful when the need for night time visibility is significant under conditions of low ambient light In retroreflective materials, the light rays impinging upon the front surface are reflected back towards the source of the illumination in a substantially parallel path. In situations where headlights or search lights on boats and aircraft are the only source of illumination, this ability to retroreflect the bulk of the rays falling thereon is especially significant for warning signs, delineators and the like.
Minnesota Mining and Manufacturing Corporation has manufactured retroreflective sheeting utilizing minute glass beads embedded in a matrix of synthetic resin to provide such retroreflection, and these materials have been sold under the trademark SCOTCHLITE. Illustrative of such materials is Bergeson et al U.S. Pat. No. 4,637,950 granted Jan. 20, 1987.
Applicant's assignee, Reflexite Corporation, has been marketing under the trademark REFLEXITE, reflective sheeting employing microprisms formations to produce such retroreflection. Illustrative of such materials is Rowland U.S. Pat. No. 3,689,346 granted Sep. 5, 1972.
Among the applications for such retroreflective materials are reflective tapes and patches for clothing of firemen, reflective vests and belts, bands for posts and barrels, traffic cone collars, highway signs, warning reflectors, and the like.
Unfortunately, many of the resins which exhibit long life when exposed to ultraviolet radiation and wide temperature fluctuations also tend to be relatively stiff. As a result, the retroreflective materials made therefrom are difficult to form or have a tendency to crack or craze when repeatedly flexed. Moreover, it is desirable to import fire retardant or resistant properties to the material so that it will function even when exposed to relatively high temperatures.
It is an object of the present invention to provide a novel method for making retroreflective sheeting using microprism formations which is relatively flexible and long lived.
It is also an object of the present invention to provide such a method which produces a retroreflective sheet material which may be readily fabricated and which is durable and readily sewn or otherwise secured to support structures.
Another object of the present invention is to provide such methods for fabricating such retroreflective sheet material which are relatively simple and relatively economical, and which produce long-lived materials.